Databases are used to store patient physiological information, such as test data, in healthcare related database systems. This data is stored in respective units. For example, blood glucose (bG) values may be stored in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). The significance of a value of 20 for blood glucose differs greatly depending on whether the units are mg/dL or mmol/L. Normal blood glucose values are generally in the range of about 4 mmol/L to about 8 mmol/L which is in the range of about 70 mg/dL to about 150 mg/dL. Returning to the value of 20, at 20 mg/dL the patient is well under the normal range while at 20 mmol/L the patient is well above the normal range. As is known, a caregiver or patient may make different therapy or lifestyle choices based on whether the value of the patient's blood sugar is above normal or below normal.
Regardless of the units in which the data is stored, the data may be presented to a user in another unit. For instance, the blood glucose values of the patient may be stored in the database in the units mg/dL and a user of a software package accessing the database may desire to have the patient blood glucose values displayed on a report in mmol/L. As is known, a conversion may be made to convert from mmol/L to mg/dL, as illustrated by equation 1.bG(mmol/L)*n=bG(mg/dL)  (1)In equation 1, n is a conversion factor. For equation 1, n is equal to about 18. As stated above, a caregiver or patient may make different therapy or lifestyle choices based on whether the value of the patient's blood sugar is above normal or below normal. As such, the value of n needs to be accurate to reflect the correct values of a patient's blood glucose to a caregiver or patient when displayed or otherwise presented in a unit different from the unit that the value is stored.
Although the exemplary blood glucose conversion given above has a single conversion factor, other conversions have multiple conversion quantities, such as converting temperature from Celsius scale to Fahrenheit scale which has both a conversion factor and a conversion offset.